Yielding driving mechanism



D. W. ALLIS.

YELDING DRIVING MECHANISM. APPLlcATloN FILED JUNE 7, 1920.

jlg PmndNov. 211, 1922.

Patented Non El., i222 f avr, were :f narran sie m., ci u DEXTER' W. ALLIS, OF WHITMAN, MASSACHUSETTS.

YIELIDING :DRIVING MECHANISML Application filed .Tune 7,

T 0 all whom t may concern:

Be it known that I, DEXTER W. ALLIs, a citizen of the United lStates, and resident ofWhitman, in the county of Plymouth and State of Massachusetts, have invented an improvement in Yielding Driving Mechanism, of which the following description, in connection with the accompanying drawings, is a specification, like letters on the drawings representing like parts'.

My present invention relates to lthemechanical transmission ofkpower andl has for its object to provide animproved and novel construction of socalled worm andA gear drivingxdevices, together with means to afford .a yielding transmission between the driving and driven members in a wormand gear construction. v

lh'ile my invention is intended vprimarily for relatively small mechanism and the form shown herfei f was devised `lfor use in4 connection with a" governr driving device7 and wherein a. relatively noiseless construction was desirable, yet the invention is not thus limited, but is of value` in any mechanism wherein a strong, economical worm and gear drive is desired, and particularly where a provision for yield or ycushioning action between the drivin and driven members, is desired. y

In carrying kout my invention have discovered that a practically noiseless power transmission can be securedl and also one whichwill wear with great evennessv and smoothness. These features, including quietness of operation, absence of shock and ar due to the yielding and cushioning features, and freedom from unduefriction, `are important. Furthermore, a very strongconstruction is secured, and a mechanism capable or transmitting power with hardened steel bearings on a shaft or aXleof softer material. 1

In many kinds of mechanism, wherein a worm-,and gear is practically necessary, but where quietness of operation is desirable,lit has been heretofore necessary to utilize one of the gears, either the worm-"or thel gear meshing therewith, to be `of ber, which, of course, wore away very quickly and easily, soon became loose and noisy, and was unsatisfactory. My improved construction is sufficiently noiseless `to be used where heretofore a iiber worm or gear was necessary.

Other features of construction, novel combinations of parts and advantages wiil be 1920.'v Serial No. 357,111.v

hereinafter more fully pointed out and claimed.

. Referring to thedrawings, illustrating preferred embodiments of my invention,

Fig. l-is a viewin conventional form showing-a worm and gear drive utilized to rotate a governor of well known type;

Fig. 2 beingk a cross-sectional view on line 2-2-of Fig. l;

Fig. 3 is a verticalv view of a similar yconstruction utilizing a plurality of `driving worm vand gear members; f

Fig-:4; being a view on the line 4t of Fig. 3.

l While' I have illustrated my. invention as applied to' a small mechanism, it will be understood that I am not 'thus' limited, the drawings being for-illustration only and showinga satisfactory and efficient use of my invention ina small'mechanism where noiselessness,compactness and eiiiciency are important. Asillustrated, any suitable framework designated at l, is adapted to carry a driving and a driven member. As here shown the driven memberl comprises the shaft V2 suitably journaled in bearings at 3 the `and et, one being in the frame l and the other in the cross-bar 5, secured to the frame by suitable retainingscrews 6, 6, as` shown. A driving shaft 101s mounted at right angles to the shaft 2 and is supported by adjustable pivot pins ll, 11, set'I through the recesses in the arms of the .frame l, as clearly illustrated, and retained in adjust-able position byset screws l2', l2. The shaft 10 in the particular construction herein shown, carries a pinion l5 adapted to mesh with any suitable source of power to rotate the same. A driving wheel 20-'ha`s its hub 21 adapted to fit onto4 the shaft l() and to be clamped thereto in desired adjusted position laterally by set screws 22, 22. This adjustment enables the driving :wheel 2() to be fitted to mesh with the worm. TWhile designate the gear wheel 20 as the driving gear, and while'this is preferable, it is to be understood that I canre'verse the driving and driven elements and have they worm member constitute the driving element if desired.l

The' construction ofv my lnovel form of worm gear will now be described. Mounted on the shaft 2 is the" worm gear element 25, this constituting a spirally wound steel strip or wire, round, ysquare'or otherwisesuitably shapedv to'mesh with-the teeth of the gear 20.

llt)

I prefer to form `this spiral worm element of suitable pitch and appropriate inner diameter, for the particular work involved and to .fit loosely but snugly, i. e., a sliding fit, on the shaft 2. For relatively small gears I find that piano wire or equivalent gives good results from which to make the worm element 25. ThisV canbe wound yin relatively long lengths and cut in short sections as desired. To constitute the driving means from the gear teeth 23 inthe `gear 20, through the spiral element 2.5, to the shaft 2, I affix to the shaft 2 a collar 26, ksecured in desired adjusted position by a set screw 27 and `having a downwardly extending` portion 28, presenting a bearing face 30. Against'this bearing 'face or edge 30 the topmost edge of the spiral worm element 25, abuts, as shown at'3l, Figsll andi2. Adjacent the bottomportion of thefshaft is` a collar 33, anda coi-led spring 35 freelyencircling theilower partof the shaft 2, bears betweenv the collar 33 thereon and the bottom collarf36,the latter resting on the crossbar or bridge f5. p

As illustrated in Figs. lv and 2,v and as above described, the'driven element'20, re-

ceiving rotation from the shaftlO, in the directionof the arrow, Fig. 2, exerts its tension through lengagement of'its teeth 23the latter 'being vbeveled slightly vto facilitate smoothnessv of bearingand action, as indicated'in'the faces 24, 24, bearing upon the spiral worm'element 25. lThe worm element 25 vis practically rigid, and with `very little yield or spring, but the bearing downwardly against the collar 33 tends to compress the spring 35 and thus permit the worm element 25,-which is not entire coil 25 to' slide vertically and down'- wardly upon the shaft 2, thusv effecting a sliding motion between the abutting' end 3l, andv the'bearing yface 30011 the collar 26 which latterl isv rigidly securedvto the shaft 2. AIn this way a yielding driving impulse is imp'arted,'and at the .same time a. smooth, practically inoiseless fand even wearing action is provided. I consider that one of the important features of this con# struction is in the fact that the gear wheel 2O has its teeth 28 bearing directly upon the longitudinal grain ofthe metal in the a cross grain cutting action between the two meshing gear members, as in ordinary 'worm f. and gear construction. Where a worm is cut into ashaft it crosses the fibers ofthe metal, and necessarily results in a greater` friction, in the wearing between the teeth and lin a grinding and noisy action, quickly wearing loose. By my construction having hardened metal worm element 25 presenting this smooth, tough, and longitudinal liber'surface to the gear wheel, I eliminate to a large degree the grinding andv undue wearing in ordinary worm and gear construction,

wound section of the driving worm gear elefment 25, but I prefer. to utilize the same as illustrated.y `While it is feasible and desirs'v able in many mechanisms to utilize a single coil 25 for the worm gear, it is also within the scope of my invention to utilize a plurality of such coils similar to the spiral 25, thus affording a greater and relatively more rigid driving action, coiled member on the worm to 'yield independently of the other, thereby automatically affording a bearing contact' between the gear wheel, or'wheels, and each element constituting the spiral. Ifhave Villustrated this capability in'Figs.v 3 and 4, wherein the same construction is utilized for illustrative purposes. In this; form the gear wheel secured to the shaft 10 is shown at V40 and provided with double the 4l than those illustrated on the gear 20. The shaft 2 is fitted with two sets of spiral wormlike elements, 44 andy 45, having the coils alternating, and each bearing upon lthe bottom collar46. The top collar, however, is here shown at 50 and is rigidly secured to the shaft 2 by a set screw 52, but is provided with a plurality of grooves, 58, to receive the upturned end portions'of the spiral elements. Asillustratedfin Fig. 4, the spiral 45 has'itsend` bent as indicated at 55 and fitted slidingly within the groove 53. I A similar construction for the end of the spiral 44 is utilized.y The operation of the apparatusl illustrated in Figs. 3k and 4 is substantially identical with that alreadyv described.

" while' "allowing each number` of gearl teeth I wherein the driving and drivenv elements seagainst the separate and independent spiral i members 44 and 45, the latter bothdepending upon the thrust of the coiled springl 35 to maintain the spiral springs with their respective ends in driving engagement iwith the xed collar 50.

In the mechanism here illustrated, the drawings Ishow a usual typeof governor, designated generally at 60, which is lsecured to the fixed collary 27 in Figs. l and 2,l and to that shown at 50 in Figs. 3 and 4. Also a bushing 61,' separate driving gear 62, and spring 63 are illustrated but are without special function in connection with my preeent invention, which is the arrangement, construction and operation of gear and Worm mechanism.

l believe that my arrangement of a spirally formed gear element such as the coiled member 25 or 44 and 45, being preferably of hardened steel and Wound slidingly upon the shaft to be driven, through which it imparts its driving power by a direct bearing at one end, is a distinct novelty and I Wish to claim the same herein broadldy.

My invention is further described and defined in the form of claims as follows:

l. A gear element, comprising a shaft and a plurality of separately formed spiral gear elements slidingly fitted on said shaft, in combination With means rigidly secured to the shaft against Which the ends oi' said plurality of members may bear with independent slidable action.

2. A. gear element, comprising a shaft and a plurality of separately formed spiral gear elements slidingly fitted on said shaft, in combination With means rigidly secured to the shaft against which the ends of said plurality of members may bear With independent slidable action in combination with. yielding means to hold said plurality of spiral elements in contact With the rigid bearing faces on the shaft.

In testimony whereof, l have signed my name to this specification.

DEXTER W. ALLS. 

